Scott, I can answer one of your questions. tmp05lnx:~ # df Filesystem 1k-blocks Used Available Use% Mounted on /dev/dasdb1 6983168 846212 5776348 13% /
The reason 5776348+846212 does not equal 6983168 is because when the mke2fs command is run, by default a certain percentage of the blocks are reserved for use only by processes running UID=0. I believe the original intent of that was so that if some user managed to fill up a file system (say /), the system administrator would still be able to logon, etc., to do cleanup. The percentage reserved is an option on the mke2fs command (-m) so if you want to make that number smaller (or larger) you can do so. It can also be adjusted after the fact with the tune2fs command (also -m). Mark Post -----Original Message----- From: Ledbetter, Scott E [mailto:[EMAIL PROTECTED]] Sent: Wednesday, July 10, 2002 1:43 PM To: [EMAIL PROTECTED] Subject: Re: Linux data on IBM RVA -snip- 3) We cannot reconcile the numbers returned by the Linux df command and what is in /proc/dasd/devices. For example for a 2.4.7 kernel ext2 filesystem on a 3390-9 (/dev/dasdb1): tmp05lnx:~ # df Filesystem 1k-blocks Used Available Use% Mounted on /dev/dasdb1 6983168 846212 5776348 13% / shmfs 843972 0 843972 0% /dev/shm tmp05lnx:~ # cat /proc/dasd/devices c723(ECKD) at ( 94: 0) is dasda:active at blocksize: 4096, 200340 blocks, 782 MB c711(ECKD) at ( 94: 4) is dasdb:active at blocksize: 4096, 1803060 blocks, 7043 MB The df command shows /dev/dasdb1 as having 6983168 1K blocks. But it also shows 846212 used, and 5776348 available. 846212+5776348=6622560. Where did 6983168-6622560=360608 blocks go to? I assume it is filesystem overhead, but 360MB of filesystem overhead seems a little high??? Then /proc/dasd/devices shows the partition as having 1803060 4K blocks. This should be 7212240 1K blocks. Another 229072 1K blocks worth of overhead? Note that 1803060*4096 does match the 7043MB number. The 6983168 blocks number from the df works out to only 6819.5 MB, and the Used+Available number of 6622560 only nets out to 6467.3 MB. So the question becomes, which number do you use to calculate utilization and compression? It appears that that 3390-9 only nets 6467MB of actual useable space due to partition and filesystem overhead. Almost 600mb of filesystem and partition overhead! Perhaps JFS, ext3 or others are more efficient, I haven't measured. Someday when I have time I'm going to crack open the source and try to figure this out. Any pointers to good filesystem tutorials will be gratefully accepted. The bottom line is that we see 2:1-3:1 compression overall for the Linux 'system' stuff. This is a relatively low number, but much of what is on the root volume are binaries. User data such as databases, Apache stuff, email, ect. compresses much better. Scott Ledbetter StorageTek -----Original Message----- From: Tony Pearson [mailto:[EMAIL PROTECTED]] Sent: July 09, 2002 3:12 PM To: [EMAIL PROTECTED] Subject: Linux data on IBM RVA List-390 readers: I have a customer writing their Linux data on an IBM Ramac Virtual Array (RVA) which has its own outboard compression. They are finding that the Linux data is not compressing at all. Has anyone else experienced this? Any ideas? Thanks Tony Pearson IBM Storage Systems - Software Architecture and Planning Storage Software for Linux on zSeries [EMAIL PROTECTED] (520) 799-4309 / tieline 321-4309
